The present invention generally relates to automatic tape loading type recording and/or reproducing apparatuses, and more particularly to an automatic tape loading type recording and/or reproducing apparatus in which a recording and/or a reproduction are carried out in a state where a tape is drawn out of a tape cassette and is wrapped around a peripheral surface of a guide drum which has heads and has a small diameter, over an angular range which greatly exceeds 180.degree..
Generally, in a video tape recorder (hereinafter simply referred to as a VTR) of the type which uses a tape cassette, a magnetic tape is wrapped around a peripheral surface of a guide drum over an angular range of approximately 180.degree., and video tracks are formed on the tape with a predetermined pattern. In such a VTR, a vertical pole and a sloping pole on the tape supply side, and a vertical pole and a sloping pole on the tape take-up side, respectively move in a plane which coincides with the height of the tape within the tape cassette, so as to carry out a tape loading operation. The guide drum is inclined by a small angle of approximately 6.degree..
Recently, there has been a development in downsizing the VTR, by maintaining magnetic tape compatibility with the existing VTR, that is, without changing the pattern of the video tracks or the like on the tape.
As one method of downsizing the VTR and still keep the above conditions satisfied, there is a method of increasing the number of video heads, reducing the diameter of the guide drum, and increasing the angular range over which the tape is wrapped around the peripheral surface of the guide drum. For example, there was a method of providing four video heads at a 90.degree. interval, reducing the diameter of the guide drum to 2/3 the diameter of the existing guide drum, and wrapping the tape around the peripheral surface of the guide drum over an angular range of approximately 270.degree. instead of the angular range of approximately 180.degree. which is employed in the existing VTR. In this case, the four video heads are switched so as to operate with an interval of 270.degree.. According to this method, the video tracks are formed on the tape with a pattern which is the same as the pattern which is in conformance with the existing standard, and the magnetic tape compatibility is maintained. Moreover, the VTR can be downsized because of the downsized guide drum.
As a method of wrapping the tape around the peripheral surface of the guide drum over the angular range of approximately 270.degree., one may consider employing the existing tape loading system which wraps the tape around the peripheral surface of the guide drum over the angular range of approximately 180.degree.. In this case, loading poles must travel over a greater distance in order to wrap the tape around the peripheral surface of the guide drum over the angular range of approximately 270.degree.. Further, due to the increased wrapping angle of the tape, the inclination angles of the guide drum and the sloping poles respectively increase. It is calculated that a rotary axis of the guide drum must be inclined by approximately 40.degree. with respect to an imaginary line which is vertical to a chassis of the VTR. The sloping angle of the sloping poles with respect to the tape must be approximately 27.degree.. When the inclination angle of the guide drum increases in this manner, the height of the guide drum increases and the guide drum occupies a large space, although the diameter of the guide drum is small. As a result, it becomes difficult to effectively downsize the VTR. On the other hand, when the inclination angle of the sloping poles increases in the above manner, it is difficult to ensure a smooth tape movement. Further, the sloping poles cannot be accommodated within the small space in the tape cassette for receiving the loading poles, and it becomes impossible to carry out an automatic tape loading operation.
A magnetic recording and/or reproducing apparatus was proposed in a U.S. patent application Ser. No. 543,924 filed Oct. 20, 1983, in which the assignee is the same as the assignee of the present application. According to this previously proposed apparatus, the inclination angle of the guide drum is approximately of the same order as the inclination angle of the existing guide drum. Further, guide poles are designed to wrap the tape around the peripheral surface of the guide drum over an angular range of approximately 270.degree..